Clamp adjustable-height seat-backs

ABSTRACT

A clamp (1) for adjustable-height seat-backs, consisting of a guide member (2) for a tubular component (3) of the seat-back and a clamping device for clamping said tubular component in the guide member, the clamping device consisting of a clamping member (10) fitted on an upper pivot to swivel on the tubular component (3) or a component beside and firmly secured to it, and an actuator (6), the actuator (6) being fitted beneath the pivot of the clamping member (10) so as to rotate behind it in relation to the tubular component (3), and the actuator (6) having at least two different diameters from its pivot.

The invention relates to a clamping arrangement for height-adjustableback rests.

Such clamping arrangements, consisting of a guide section for a tubularsection of the back rest and a clamping means such as a screw forclamping the tubular section in the guide section, have long been known.Known from DE-U-295 10 446.5 is a back rest clamping arrangement inwhich a clamping body can firmly engage with the tubular section of aback rest by means of a laterally arranged. However, known clampingarrangements often have the disadvantage that the tubular section willloosen in time.

The objective of the present invention is to create a clampingarrangement for height-adjustable chair back rests which will not loosenover the long term and which are easy and comfortable to operate.

Further developments and advantageous embodiments of the invention aredescribed hereinafter.

According to the invention, a clamping arrangement for clamping thetubular section of a back rest consists of a clamping body pivotablymounted to an upper pivot point to swivel on the tubular section in theguide section or an adjacent section firmly mounted to same, and anactuator body, whereby the actuator body is pivotably arranged behindthe clamping body, below the pivot point of the clamping body, to swivelon the tubular section, and whereby the actuator body has at least twodifferent diameters, seen from its pivot axis.

According to a preferred embodiment of the invention, the actuator bodyhas a helical cross section. The clamping body is mounted on a bolt inthe lower guide section by a pivot arm pointing downward, and the bottomend of the pivot arm adjoins the actuator body in at least one of itspositions.

It is an advantage when the clamping body or the pivot arm is providedwith an elastically mounted catch for a recess in the tubular section ofthe back rest.

The invention is described below by way of example and with reference tothe drawings, in which:

FIGS. 1 to 3 show three views of a clamping arrangement including asectional view in FIG. 1;

FIGS. 4 to 6 show three views of the clamping body of FIGS. 1 to 3.

The clamping arrangement according to FIGS. 1 to 3 consists of a guidesection 2 with one rear wall and two lateral walls, so that the top viewshows a U-shaped cross section, whereby the rear wall is provided withtwo inwardly bent notches 2', so that a tubular section 3 of a back restcan slide in the guide formed by notches 2' and the rear wall, and of aclamping means for clamping tubular section 3 in the desired insertiondepth. The clamping means consists of a clamping body 10 which togetherwith a pivot arm 4 is pivotably mounted to a bolt 5 which is attachedlaterally and above in guide section 2, and of an actuator body 6. As isshown in the top view, clamping body 10 adjoins the tubular section 3.For this purpose, as is shown more clearly in FIG. 5, its contour 14 isadapted to tubular section 3. The clamping body 10 is fastened to theside walls of pivot arm 4 by means of a pin 12, catches or some such.For bolt 5, it is provided in its rear wall with a groove 17 shown indetail in FIG. 4. The rear wall of pivot arm 4 is recessed in this area.In the position shown, the clamping body 10 only adjoins tubular section3 and does not clamp it. The side walls of guide section 2 are providedwith holes 9 for fastening to a seat carrier.

Pivot arm 4, which in top view has a U-shaped cross section open towardthe tubular section 3, and whose side walls partially surround clampingbody 10, is extended toward the bottom and can be made to engage with anactuator body 6. The actuator body 6 is mounted on a pivotable lateralbolt 7 in the side walls of guide section 2. As shown in FIG. 3, lateralbolt 7 is extended on one side and provided with a hand wheel. In thecross sectional view, the actuator body 6 has a helical contour. In FIG.3, the side of actuator body 6 with the smallest circumference is turnedtoward the bottom end of pivot arm 4. If the actuator body 6 is turnedclockwise, the side with the greater circumference will finally pressupon pivot arm 4, which causes clamping body 10 to be pressed onto thetubular section 3. The result is a very high clamping force.

Tubular section 3 is secured against unintentional pulling-out andoverly deep insertion. Integrated in clamping body 10 is a pull-outstop. It consists of a latch 11 pivotably mounted on bolt 5. As FIG. 6shows, clamping body 10 is provided with a vertical groove 16 for thispurpose. Latch 11 extends downward in groove 16 and is provided with arecess for pin 12 or catches or some such, which also limits the path oflatch 11. Latch 11 is charged by a spring 13 which is mounted on ajournal between the bottom end of latch 11 and the rear wall of pivotarm 4. Thus, latch 11 pushed onto tubular section 3. If the same ispulled out, latch 11 locks in an opening 3' at the bottom end of tubularsection 1 and is stopped. When tubular section 3 is pushed in, latch 11slides out of opening 3' without resistance. Guide section 2, below thechannel for the tubular section, is provided with a nose 18 whichprevents that the tubular section is pushed through farther.

I claim:
 1. Clamping arrangement which clamps a tubular section of achair height-adjustable back rest on a chair guide section definingtubular section receptive structure, the clamping arrangement comprisinga clamping body pivoted on the guide section and disposed adjacent thetubular section, an actuator body pivotably mounted in the guide sectionbelow a pivot location of the clamping body in relation to the tubularsection, and a pivot lever pivot mounted at an end thereof on a commonaxis with the clamping body and fastened with said clamping body, anopposite end of the pivot lever locating proximal said actuator body,the actuator body having a circumferential contour with two differentdiameter section as seen from a pivot axis thereof, one circumferentialdiameter section having a diameter greater than a diameter of a othercircumferential sections, rotation of said actuator diameter sectionbody in a given direction bring said one circumferential diametersection thereof into pressing contact with the opposite end of saidpivot lever whereby said pivot lever presses said clamping body againstthe tubular section therewith clamping same, rotation of said actuatorbody in an opposite direction to bring the other circumferentialdiameter section proximal said pivot lever opposite end disengagingcontact between said actuator body and said pivot lever opposite end. 2.Clamping arrangement for a chair height-adjustable back rest accordingto claim 1, in which the actuator body two circumferential sectionsdefine a helical surface contour.
 3. Clamping arrangement for a chairheight-adjustable back rest according to claim 1, in which one of theclamping body and the pivot lever is provided with an elasticallymounted catch or latch for a recess in the tubular section of the backrest.